"Star Wars," "Star Trek," "Battlestar Galactica" -- laser technology plays a pivotal role in science fiction movies and books. It's no doubt thanks to these sorts of stories that we now associate lasers with futuristic warfare and sleek spaceships.

­But lasers play a pivotal role in our everyday lives, too. The fact is, they show up in an amazing range of products and technologies. You'll find them in everything from CD players to dental drills to high-speed metal cutting mac­hines to measuring systems. Tattoo removal, hair replacement, eye surgery -- they all use lasers.
But what is a laser? What makes a laser beam different from the beam of a flashlight? Specifically, what makes a laser light different from other kinds of light? How are lasers classified?

In this article, you'll learn all about the different types of lasers, their different wavelengths and the uses to which we put them. But first, let's start with the fundament­als of laser technology: go to the next page to find out the basics of an atom.

Atoms: the building blocks of life and the universe. We're all made of these microscopic bits of matter, but how many does it take to make a complete human being? And exactly what kinds of atoms do we have inside us?